Mechanism of nitrogen loss driven by soil and water erosion in water source areas

Nitrogen (N) present in drinking water as dissolved nitrates can directly affect people's health, making it important to control N pollution in water source areas. N pollution caused by agricultural fertilizers can be controlled by reducing the amount of fertilizer applied, but pollution caused by soil and water erosion in hilly areas can only be controlled by conservation forests. The catchment area around Fushi Reservoir was selected as a test site and mechanisms of N loss from a vertical spatial perspective through field observations were determined. The main N losses occurred from June to September, accounting for 85.9-95.9% of the annual loss, with the losses in June and July accounting for 46.0% of the total, and in August and September for 41.9%. The N leakage from the water source area was effectively reduced by 38.2% through the optimization of the stand structure of the conservation forests. Establishing well-structured forests for water conservation is crucial to ensure the security of drinking water. This preliminary research lays the foundation for revealing then loss mechanisms in water source areas and improving the control of non-point source pollution in these areas.